Origin of 79mph Train Speed Limit

Why not 80? or 85?

and where did we get the odd number of 69mph for freight?

and is there some optimal speed for fuel consumption on a train running across flat plains with X number of trailers or autoracks(These seem to have the least drag)

it is not to exceed 80 mph , which has been translated as 79 mph .

It may have some thing to do with the physics of a moving passenger train. In Japan, trains running on lines with grade crossings are restricted to a top speed of 130km/h (80mph) as this is the fastest a train can run while still being able to brake to a stop within 600m. Of course, all JR lines and most (all?) private railways in Japan are equipped with positive train control, and have been since the mid sixties.

This site has an explanation of the varying regulations:

http://tacnet.missouri.org/history/railroads/fra.html

Scroll down on that page to see the explanation of 79 mph, but it's as David Benton says - 79 mph is just below 80 mph, at which a train needs cab signaling or automatic train stop. 69 mph is probably a restriction placed by an individual railroad, and could be based on excessive wear and fuel usage at 70 mph or above, or possibly curve geometry that would cause instability above 69 mph. The track structure would have to be in FRA Class 4 or 5 condition to allow speeds above 60 mph, whatever the case.

80 mph is the minimum speed where a railroad must have cab signals.

I remember someone once pointing out that BART trains' top speed is 1 mph more than Amtrak's in the San Francisco Bay Area. That's because BART trains have cab signals: a display of maximum speed.

There are two sets of speed limits set by Federal regulatory agencies for railroads. The first are the old ICC regulations, based on type of signal control or type of operation. Speeds of "80 MPH or more" require cab signals OR automatic train stop, so 79 MPH is the max if you don't have those. "Less than 60 mph" is the limit for unsignaled track for passenger trains (59 MPH), and "less than 50 MPH" (49) for freight trains. Within yard limits, the rule is "less than 20 mph", which on some railroads will show as a speed of 19.

FRA's Track Safety Standards define nine classes of track, each with a maximum speed for freight and passenger. They are:

Class 1 10/15
Class 2 25/40
Class 3 40/60
Class 4 60/80
Class 5 80/90
Class 6 110
Class 7 125
Class 8 150 (Amtrak limits freights to 50 on their Class 8 track)
Class 9 180, passenger trains only (no freight permitted)

The lower of the track class speed or the control type speed applies, so on Class 4 track, passenger max is 79.

When did Class 9 drop to 180 mph? It used to be 200. So if we want trains to run at 186 mph, they'll have to invent a Class 10?

Wonder how well those high-speed trains really run on that UIC 60 track (121 lb/yd).

amtrakowitz wrote:When did Class 9 drop to 180 mph? It used to be 200. So if we want trains to run at 186 mph, they'll have to invent a Class 10?

Wonder how well those high-speed trains really run on that UIC 60 track (121 lb/yd).

It appears to be still 200 MPH.

From the FRA website - http://www.fra.dot.gov/

You can download the PDF - FRA Track Standards and Inspection Fact Sheet -

http://www.fra.dot.gov/downloads/PubAff ... _FINAL.pdf

It is dated Feb 2008. Looking at 49 CFR Part 213 - it too shows 200 MPH for Class 9.

Gil, known as Bill somedays ...

Up until the FRA-mandated certification of engineers in about 1992, the 79
MPH limit was occasionally exceeded when a crew wanted to make up time. In the '70's and early '80's it was not unusual for a train like the SILVER METEOR, CITY OF NEW ORLEANS or CAL ZEPHYR to approach 90. No more - an engineer can't risk being taken out of service for a radar violation or inspection of event recorder tapes when there is an incident.

Andy

Why max speed of 59 in manual block cause at speeds 60 and over a signal system is required.
Why max speed of 79 in signalled territory, cause at speeds 80 and over cab signal is required.

DutchRailnut wrote:Why max speed of 59 in manual block cause at speeds 60 and over a signal system is required.
Why max speed of 79 in signalled territory, cause at speeds 80 and over cab signal is required.

Actually, those speed restrictions are fairly close to the historical speed limits railroads imposed on themselves before the FRA. It seems to me that well considered industry practices were simply enshrined in regulation.

So with new tracks on the Empire Water Level route what is it really capable of? and assuming a 6 car Amtrak train is doing 100mph or 90 mph how much stopping distance does it need with disc brakes on amfleet cars?

gearhead wrote:So with new tracks on the Empire Water Level route what is it really capable of? and assuming a 6 car Amtrak train is doing 100mph or 90 mph how much stopping distance does it need with disc brakes on amfleet cars?

Back in the days of the New York Central, 4 tracks, dedicated freight and passenger, but signaled in just one direction, with automatic train stops, temporal separation since passenger trains mostly moved in evening hours, freights at night, with all of that......the speed limit was at most 85 MPH.

So, really, what's the difference between 79 MPH and 85 MPH? Not much. Delays are more important than outright speed, and if Amtrak can't keep a schedule, an Empire Service train is late getting out of Sunnyside, or if the Lake Shore is held up in Renesselear for a couple of hours, or delayed before it gets to Schenectady, the passenger train loses its slot and is in conflict with up to half a dozen freight. When CSX has a lot of traffic, the delays keep piling up. So outright speed really doesn't matter.

And actually, the third track doesn't matter at all if the ancient Livingston Avenue bridge isn't replaced. That should be the priority.